Active material for lithium secondary battery composite electrode for improving output and lithium secondary battery including the active material

Abstract

Provided is a composite electrode for a lithium secondary battery for improving output and a lithium secondary battery including the composite electrode, in which, in a composite electrode having two or more active materials mixed therein, an active material having a small particle size is included in the composite electrode by being coagulated and secondarily granulated so as to allow mixed active material particles to have a uniform size, and thus, electrical conductivity is improved to have high output characteristics.

What is claimed is: 
     
       1. A composite electrode comprising:
 a current collector; and 
 a single layer disposed on the current collector, wherein the single layer comprises a mixture of secondary particles of a first active material and particles of a second active material, 
 wherein the secondary particles comprise primary particles of the first active material and a conductive agent, wherein the primary particles have a particle size ranging from about 5 nm to about 200 nm, wherein the conductive agent is present on the surface of and inside of the secondary particles, and wherein the conductive agent is included in an amount range of 0.5 wt % to 5 wt % based on a total weight of the secondary particles, 
 wherein the particles of the second active material consist essentially of primary particles of the second active material having a particle size ranging from about 5 μm to about 20 μm, 
 wherein the secondary particles of the first active material have a particle size uniform with the particles of the second active material, 
 wherein the secondary particles are present in an amount ranging from about 30 wt % to about 80 wt % of a total amount of the first active material in the composite electrode, 
 wherein the first active material is LiFePO 4 , and 
 wherein the second active material is ternary lithium-containing metal oxide expressed as Chemical Formula 2:
   LiNi x Mn y Co 1-x-y O 2 , 0< x< 0.5, 0< y< 0.5  [Chemical Formula 2].
 
 
 
     
     
       2. The composite electrode of  claim 1 , wherein the first active material is included in an amount range of about 10 wt % to about 60 wt % based on a total amount of the composite electrode. 
     
     
       3. The composite electrode of  claim 1 , wherein the conductive agent is a mixture of one or more selected from the group consisting of carbon black including acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermal black, or a material having a crystal structure of graphene or graphite. 
     
     
       4. The composite electrode of  claim 1 , wherein the composite electrode is a cathode. 
     
     
       5. The composite electrode of  claim 1 , wherein the second active material is ternary lithium-containing metal oxide expressed as Chemical Formula 2:
   LiNi x Mn y Co 1-x-y O 2 , ⅓≤ x< 0.5, ⅓≤ y< 0.5.  [Chemical Formula 2]
 
 
     
     
       6. The composite electrode of  claim 5 , wherein the ternary lithium-containing metal oxide is Li[Ni 1/3 Co 1/3 Mn 1/3 ]O 2 . 
     
     
       7. The composite electrode of  claim 6 , wherein the composite electrode further comprises a mixture of one or more selected from the group consisting of lithium cobalt oxide, lithium nickel oxide, lithium cobalt-nickel oxide, lithium cobalt-manganese oxide, lithium manganese-nickel oxide, lithium cobalt-nickel-manganese oxide, lithium-containing olivine-type phosphate, and oxides having other elements substituted or doped therein, and the other elements are one or more elements selected from the group consisting of Al (aluminum), Mg (magnesium), Mn (manganese), Ni (nickel), Co (cobalt), Cr (chromium), V (vanadium), and Fe (iron). 
     
     
       8. The composite electrode of  claim 1 , further comprising a binder and a second conductive agent in an amount of about 10 wt % or less based on the total amount of the composite electrode. 
     
     
       9. A lithium secondary battery comprising the composite electrode of  claim 1 . 
     
     
       10. The lithium secondary battery of  claim 9 , wherein the lithium secondary battery is used as a unit cell of a battery module in a power source of a device. 
     
     
       11. The lithium secondary battery of  claim 10 , wherein the device is a power tool; an electric vehicle (EV) including an electric car, a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); an electric two-wheeled vehicle including an E-bike and an E-scooter; an electric golf cart; an electric truck; and an electric commercial vehicle or a power storage system. 
     
     
       12. The composite electrode of  claim 1 , wherein the secondary particles are present in an amount ranging from about 30 wt % to about 70 wt % of a total amount of the first active material in the composite electrode. 
     
     
       13. The composite electrode of  claim 1 , wherein the secondary particles are present in an amount ranging from about 30 wt % to about 60 wt % of a total amount of the first active material in the composite electrode. 
     
     
       14. The composite electrode of  claim 1 , wherein the secondary particles are present in an amount ranging from about 30 wt % to about 75 wt % of a total amount of the first active material in the composite electrode. 
     
     
       15. The composite electrode of  claim 1 , wherein the secondary particles are present in an amount ranging from about 30 wt % to about 50 wt % of a total amount of the first active material in the composite electrode.